First melt 100g chopped butter at 60 degrees speed 2 for 5 minutes. Add a packet of granita biscuits and pulse at turbo 3 or 4 times until evenly smashed up and mixed with the butter. Press this into the base and sides of your lined springform tin and chill while you do the filling.
Clean your Thermo bowl and whip 1 cup of pure cream to soft peaks and set aside in a large bowl. In a separate bowl melt 4 tsp powdered gelatine with 1/3 cup boiling water. Also finely zest 1 lemon and squeeze 1/3 cup of lemon juice.
Next combine 500g softened cream cheese and 1 tin condensed milk (I used low fat and it worked fine) and mix together speed 4 until smooth. Pour in your melted gelatine and lemon juice and zest and mix again speed 4 for 15 seconds. Pour this mix into the large bowl where your whipped cream is waiting and gently fold together until well mixed being careful to keep the lightness from the whipped cream.
Pour into your biscuit case and tap gently to settle and then chill in the fridge at least 3 hours or overnight until set.